The long-term objective of this research is to gain an understanding of the process of cellular aging at the molecular level and to define those genes and molecules that determine longevity. The studies will be carried out in the budding yeast Saccharomyces cerevisiae, which we have recently developed as a model system for the study of cellular aging, by devising the techniques necessary for the bulk preparation of yeast cells of any desired generation (age). The specific objectives of the project include the continuation and expansion of the search for genes that are differentially expressed during the life-span. This endeavor will be carried out using both differential and subtractive hybridization approaches to identify young, middle age and old cell-specific genes. These genes will be characterized, and their patterns of expression during the life-span will be examined in detail, as a means of classification. The effects of disruption and overexpression of selected age-related genes on the life-span will be determined to identify those genes whose activity is causally connected with cellular aging. Furthermore, the upstream regions of these genes will be examined for the presence of possible age-responsive regulatory elements by means of nucleotide sequencing and by fusion with lacZ as a reporter gene. In addition to these molecular approaches, a search for mutants possessing an altered life-span will be instituted to aid in the elucidation of the putative genetic program leading to cell senescence and to increase the likelihood of identifying regulatory genes that affect life-span. Finally, the possible role of Ty transposition in aging will be evaluated. The proposed studies should provide insights into the molecular cell biology of the aging process, and they will allow an evaluation of the relative contributions of genetic programs and random errors to cellular senescence. The proposed research is directly applicable to the area of aging in humans, and it is also relevant to the cancer problem.